1. Field of Invention
The invention relates to a shoe having a spring-position limitation for use, in particular, in a torsional-vibration damper and to a torsional-vibration damper having end shoes and/or slide shoes designed on the basis of such shoe.
2. Description of Related Art
EP 1 584 839 A1 discloses a torsional vibration damper having a drive-input-side primary element which has at least one primary driver and having a drive-output-side secondary element which has at least one secondary driver, which primary element and secondary element can be rotated relative to one another about a neutral position counter to at least one spring element which is provided between one of the primary drivers and one of the secondary drivers, and having end shoes arranged on the end sides of the spring elements, with at least one of the end shoes being designed such that, when a threshold relative rotational angle with respect to the neutral position is reached, at least one of the drivers comes into direct contact with the spring element, bypassing the at least one end shoe.
Torsional vibration dampers or rotary vibration dampers are known in different variations and from different applications. They are provided in particular in automotive engineering for elastically coupling the internal combustion engine and drivetrain. In this way, it is sought to prevent vibrations from being transmitted from the internal combustion engine to the drivetrain or gearbox. Such a transmission of vibrations occurs in motor vehicle drives in particular in the case of internal combustion engines with comparatively few cylinders and at low rotational speeds. Effective damping of such vibrations makes it possible for the internal combustion engine to be operated at relatively low rotational speeds, which generally entails a reduced fuel consumption and is therefore both economically and ecologically advantageous.
Torsional vibration dampers having a drive-input-side primary element and a drive-output-side secondary element which are coupled to one another by means of a spring device and which are rotatable with respect to one another to a limited extent about a rotational axis are known for example from EP 1 371 875 A1 or DE 195 22 718 A1. The primary element comprises a first driver which will also be referred to below as the primary driver. The secondary element comprises a second driver which will also be referred to below as the secondary driver. The torque is transmitted from the primary element by means of the primary driver firstly to the spring device and from there to the secondary driver of the secondary element.
The spring device is generally composed of one or more spring elements arranged in series in the circumferential direction of the torsional vibration damper, preferably helical springs or helical spring sets which are if appropriate connected to one another by means of slide shoes and are supported at both end sides by means of end shoes against the respective driver. If a transmission of torque takes place from the primary element to the secondary element, the described transmission of torque is referred to as traction. If, in contrast, the transmission of torque takes place in the opposite direction from the secondary element to the primary element, this is referred to as overrun.
It has been found that, in the event of a traction/overrun shift, in particular under low load conditions, a changeover noise can be heard. This can be attributed to the fact that, during the traction/overrun shift, the drivers of the primary and secondary elements abut against the end shoes which support the spring elements, and this can cause the changeover noise mentioned.
For this reason, in DE 101 33 694 A1, additional spring elements were provided between the end shoes and the drivers in order to reduce the abutment of these against one another and the associated generation of noise.
In contrast, in DE 199 58 814 A1, such additional spring elements are dispensed with and, instead, the end shoe which bears against the end side of the respective spring element is designed so as not to completely cover the end side of the spring element. Furthermore, the drivers are provided with an arm which is designed such that, in the event of an abutment of the driver and end shoe against one another, the arm of the driver firstly abuts directly against the spring element, bypassing the end shoe. In this way, the movement of the driver is initially damped slightly before the driver abuts over a large area against the end shoe, such that the abovementioned changeover noises can be reduced at least in the event of small torques to be transmitted. A disadvantage of the device is that the initial damping effect is not great enough if the driver is acted on with a high rotational impetus or a high torque. In this case, changeover noises are still generated as the driver abuts against the stop.
Generally known from EP 0 236 159 is a torsional vibration damper in which use is made of two differently-dimensioned types of springs, with the first of the springs being connected in each case alternately in series with the second of the springs.
DE 102 40 839 A1 discloses a torsional vibration damper in which, within the windings of a first spring, a second spring with a smaller outer diameter is inserted. Here, the second spring projects at the end side slightly out of the end side of the first spring. Here, the two springs are mounted in each case entirely within a common end stop, such that undesirable noises are generated in the event of an abutment of a driver.
DE 199 09 044 A1 describes a further arrangement of a torsional vibration damper of this type, with the second spring having, in its central section, a spring winding with an increased diameter, which spring winding engage between two adjacent spring windings of the first, outer spring and thereby fix the second spring in the first spring. In this arrangement, the second, inner spring is dimensioned so as to be harder than the outer spring. The two springs are again mounted at the end side on in each case one end stop or driver.
DE 100 19 873 A1 describes a torsional vibration damper having a multiplicity of springs which are mounted in slide shoes. Here, partially differently dimensioned first and second springs alternate in the circumferential direction.
DE 41 41 723 C2 describes a torsional vibration damper having an idling spring system. In this arrangement, too, differently dimensioned springs are inserted in the circumferential direction.
The problem on which the invention is based is that of proposing, in a simple manner, a shoe having a spring position limitation and having two springs which are arranged one inside the other, such that improved isolation and vibration damping can be realized. Furthermore, it is sought to propose a torsional vibration damper using a shoe of this type in the form of end shoes and/or slide shoes.